2011年8月气候异常及成因分析

在总结2011年8月我国气候异常与大气环流特征的基础上,针对西南干旱和热带气旋活动偏少两大气候异常事件的成因进行了分析。结果表明：高度场偏高、西太平洋副热带高压偏强、夏季风偏弱和水汽条件较差等大气环流异常是导致高温干旱的主要原因;中部型拉尼娜事件的滞后影响和印度洋偏暖的影响是西南干旱的重要外强迫条件。南海对流活动偏弱,菲律宾以东季风槽位置偏北,热带气旋活动区域垂直风切偏大,西北太平洋副热带高压偏强等因素导致热带气旋活动偏少。     

Evolution of aerosol vertical distribution during particulate pollution events in Shanghai

A set of micro pulse lidar(MPL)systems operating at 532 nm was used for ground-based observation of aerosols in Shanghai in 2011.Three typical particulate pollution events(e.g.,haze)were examined to determine the evolution of aerosol vertical distribution and the planetary boundary layer(PBL)during these pollution episodes.The aerosol vertical extinction coefficient(VEC)at any given measured altitude was prominently larger during haze periods than that before or after the associated event.Aerosols originating from various source regions exerted forcing to some extent on aerosol loading and vertical layering,leading to different aerosol vertical distribution structures.Aerosol VECs were always maximized near the surface owing to the potential influence of local pollutant emissions.Several peaks in aerosol VECs were found at altitudes above 1 km during the dust-and bioburning-influenced haze events.Aerosol VECs decreased with increasing altitude during the local-polluted haze event,with a single maximum in the surface atmosphere.PM2.5 increased slowly while PBL and visibility decreased gradually in the early stages of haze events;subsequently,PM2.5 accumulated and was exacerbated until serious pollution bursts occurred in the middle and later stages.The results reveal that aerosols from different sources impact aerosol vertical distributions in the atmosphere and that the relationship between PBL and pollutant loadings may play an important role in the formation of pollution.     

Assessing modern arboreal phytolith sensitivity to vegetation variations in temperate forest regions

To assess the reliability of arboreal phytoliths for differentiating vegetation types in temperate forest regions, we systematically analysed arboreal leaf phytoliths from 72 arboreal plants and 49 modern soils from three forest types in northeast China. The arboreal leaf phytolith production and morphotypes were highly variable between species. The arboreal leaf phytolith assemblages could clearly distinguish between broadleaf and coniferous species, but they were much less successful in differentiating broadleaved trees into subtaxa. Coniferous leaf morphotypes were successfully used to differentiate coniferous trees into families and subtaxa, especially in the Pinaceae. Two diagnostic broadleaved and six coniferous phytolith morphotypes were recognized within the modern soil beneath forest ecosystems. These arboreal phytoliths comprised up to 10–15% of the total soil phytoliths, and were dominated by coniferous types. Arboreal phytolith concentrations and phytolith assemblages in the soils fluctuated substantially amongst the three forest types. Soil arboreal phytolith assemblages were successfully used to differentiate samples from Larix mixed forest, broadleaf forest and Pinus koraiensis mixed forest. In addition, the arboreal index quantitatively distinguished the three forest types, with B/BE values <0.4 for Larix mixed forest samples, values from 0.4 to 0.6 for broadleaf forest samples, and values from 0.6 to 0.9 for P. koraiensis mixed forest. Thus, our surface soil arboreal phytolith assemblages and arboreal index are a useful reference for differentiating forest ecotypes, and they also provide reliable analogues for arboreal phytoliths from palaeoecological contexts in temperate forest regions.     

AN ANALYSIS ON THE STRUCTURE TYPES AND BENEFITS OF SLOPELAND AGROFORESTRY SYSTEMS-Taking the Three Gorge Reservoir Area As An Example

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Deglaciation and catchment ontogeny in coastal south‐west Greenland: implications for terrestrial and aquatic carbon cycling

Here we present Holocene organic carbon, nitrogen, sulphur, carbon isotope ratio and macrofossil data from a small freshwater lake near Sisimiut in south‐west Greenland. The lake was formed c. 11 cal ka BP following retreat of the ice sheet margin and is located above the marine limit in this area. The elemental and isotope data suggest a complex deglaciation history of interactions between the lake and its catchment, reflecting glacial retreat and post‐glacial hydrological flushing probably due to periodic melting of local remnant glacial ice and firn areas between 11 and 8.5 cal ka BP. After 8.5 cal ka BP, soil development and associated vegetation processes began to exert a greater control on terrestrial–aquatic carbon cycling. By 5.5 cal ka BP, in the early Neoglacial cooling, the sediment record indicates a change in catchment–lake interactions with consistent δ¹³C while C/N exhibits greater variability. The period after 5.5 cal ka BP is also characterized by higher organic C accumulation in the lake. These changes (total organic carbon, C/N, δ¹³C) are most likely the result of increasing contribution (and burial) of terrestrial organic matter as a result of enhanced soil instability, as indicated by an increase in Cenococcum remains, but also Sphagnum and Empetrum. The impact of glacial retreat and relatively subdued mid‐ to late Holocene climate variation at the coast is in marked contrast to the greater environmental variability seen in inland lakes closer to the present‐day ice sheet margin. Copyright © 2012 John Wiley & Sons, Ltd.     

The July 10, 2020, red-bed landslide triggered by continuous rainfall in Qianxi,Guizhou, China

Landslides - On July 10, 2020, a catastrophic landslide with a slope angle of only 8° occurred in the red-bed series strata in Qianxi, Guizhou, southwestern China, due to prolonged rainfall,...     

Study on indium occurrence state and enrichment patterns in the Xianghualing Sn-Pb-Zn orefield in southern HunanSCIEI北大核心CSCD

In作为一种分散元素,通常极难形成独立矿床,而主要以伴生组分的形式赋存在锡多金属矿床中。香花岭矿田蕴藏着丰富的Sn、Pb、Zn等矿产资源,是我国潜在的In资源基地,但目前该矿田中In的赋存状态、分布规律及成矿潜力尚不清楚。鉴于此,本文以香花岭矿田3个典型锡多金属矿床(新风、铁砂坪、茶山)为研究对象,在野外地质及矿相学观察的基础上,采用ICP-MS、EPMA和LA-ICP-MS开展了全岩地球化学和闪锌矿元素地球化学研究。结果表明,In主要以类质同象的形式富集在闪锌矿中,可能的替代方式为In^(3+)+Cu^(+)2←→Zn^(2+)。不同矿床中In的富集程度明显不同,其中,新风最富In(平均品位213.7g/t),其次为茶山,而铁砂坪最贫In。发现当闪锌矿中Cd含量介于5000×10^(-6)~7000×10^(-6)区间时,对应的In含量最高(>1000×10^(-6))。3个矿床的闪锌矿均富集Fe、Mn、In等高温元素,显著亏损Ga和Ge等低温元素。通过对比发现,这些闪锌矿与典型中高温岩浆-热液矿床(如远端矽卡岩型矿床)中闪锌矿的元素地球化学特征相似,应用闪锌矿地质温度计估算的结晶温度为345~372℃,且新风闪锌矿温度略高。闪锌矿中In的含量主要受温度控制,越靠近岩体、温度越高的闪锌矿越富In。结合前人资料,估算香花岭矿田伴生In资源量超过15000t,潜在经济价值巨大,应予以回收利用。     

Distribution characteristics and differential enrichment mechanism of rhenium in molybdenite in the Dexing copper ore fieldSCIEI北大核心CSCD

世界上绝大部分Re赋存在斑岩型矿床的辉钼矿之中,且分布极不均匀。在矿床-矿石-矿物颗粒等不同尺度上,Re含量均存在较大差异,但造成这些差异的因素目前尚不清楚。本文以德兴矿田中富家坞和铜厂二个矿床的辉钼矿为研究对象,在细致的矿相学研究的基础上,对其开展了EPMA、LA-ICP-MS和XRD分析,同时结合前人研究资料,详细探讨了Re在这两个矿床辉钼矿中的分布规律及差异性富集机制。结果显示:富家坞和铜厂均普遍发育两种形态的辉钼矿(细粒集合体型和粗粒片状型),Re在两种辉钼矿中的分布均极为不均,但细粒集合体型相对更富Re,而同一形态辉钼矿铜厂矿床则具有更高的Re含量;同一矿床中辉钼矿结晶越晚,往往越富集Re;个别辉钼矿可见扭结现象,且扭结部位的Re含量更低,暗示后期构造变形可能导致了Re的丢失;两个矿床高Re辉钼矿和低Re辉钼矿的结构均为2H多型,表明Re含量与辉钼矿晶体结构无关。结合前人资料,本文认为成矿流体性质(如温度、盐度等)是导致铜厂和富家坞辉钼矿Re含量差异的主要因素。